In a known embodiment of the open-end spinning machine, a bundle of fibers supplied from an upstream supplying mechanism is opened by means of a combing roller, so as to separate the bundle into individual fibers, and the separated fibers are carried into a twisting mechanism so as to form a twisted yarn. In such an open-end machine, a combing roller provided with a metallic wire helically secured on the peripheral surface of the main body of the combing roller is utilized.
It is well known that the above mentioned metallic wire is provided with a cross-section comprising a laterally expanded base portion and a teeth portion projected upward from the base portion. When the metallic wire is mounted on the peripheral surface of the main body of the combing roller, the base portion of the metallic wire is pressed into a helical groove formed on the peripheral portion of the main body of the combing roller by means of a press roller, so that the metallic wire can be rigidly mounted on the main body of the combing roller. To attain an effective action of the combing roller, the helical groove is formed on the peripheral portion of the main body with a pertinent pitch along the axial direction of the combing roller. It is well known that the main body is coaxially provided with a flange at each end thereof. Therefore, in such a combing roller, cylindrical spaces are formed on the peripheral portion of the main body between the two flanges and the corresponding spiral portions of the metallic wire, which are the starting and terminal portions of the metallic wire. The axial size of those cylindrical spaces has been allowed to be almost the same as the above-mentioned pitch of the helical groove, that is the axial pitch of the metallic wire. It is the understanding of the inventors of the present invention that the reasons for the above-mentioned axial size of those cylindrical spaces are as follows. First since the mounting of the metallic wire on the main body of the combing roller is carried out by pressing the shoulder of the base portion of the metallic wire into the helical groove of the main body by means of a pressing disc having a certain thickness, it is necessary to have a space for carrying out the pressing operation when the pressing operation is carried out on the portions of the wire closest to the above-mentioned flanges, and; second, it is not recognized that the cylindrical spaces at the two end portions of the main body of the combing roller give rise to a serious problem.
According to the technical principle of the open-end spinning method, it is essential to feed well separated individual fibers into a yarn forming mechanism, such as a spinning rotor, and the function of the combing roller is to do this. Therefore, generally speaking, the body of the combing roller and the metallic wire are made with precision, and the mounting of the metallic wire on the main body of the combing roller is carried out with precision, so as to ensure the function of the combing roller. However, it is the experience of the inventors of the present invention that, even if the combing roller is made with precision as mentioned above, it is quite difficult to eliminate possible creation of slubby portions in the twisted yarn, and it is their understanding that one reason for the creation of such slubby portions is due to the defective functioning of the conventional combing roller which results from the above mentioned cylindrical spaces.
Therefore, the principal object of the present invention is to provide an improved combing roller which does not give rise to the above mentioned defective function of the conventional combing roller.
To attain the purpose of the present invention, an analysis of the action of the conventional combing roller was carefully carried out, and it was found that the above-mentioned cylindrical spaces formed at both of the axial end portions of the main body of the combing roller and free from the combing action even though a part of a supplied handle of individual fibers is introduced therein. Consequently, it is possible for blocks of entangled fibers to be fed into the yarn forming mechanism, such as the spinning rotor. The above-mentioned cylindrical spaces are hereinafter referred to as free spaces. Based on the above-mentioned result, the inventors of the present invention have devised the following described combing roller to attain the purpose of the present invention. That is, in the combing roller, if the rotation of the combing roller is counter-clockwise and a right hand helical groove for receiving the base portion of the metallic wire is formed on the cylindrical surface of the main body, and the base portion of the metallic wire is rigidly inserted into the above-mentioned helical groove in such condition that the working surface of each tooth of the metallic wire faces the direction of the combing roller, the teeth of a terminal portion of the metallic wire adjacent to the flange at the end of the roller corresponding to the direction of progress of an imaginary right hand screw turned in the counter-clockwise direction when in imaginary screw engagement with the right hand helical groove are bent toward the above-mentioned flange, so that the axial size of the free space between the above-mentioned flange and the above-mentioned terminal portion can be reduced remarkably from that of the known combing roller; while if the combing roller is turned counter-clockwise direction and the metallic wire is rigidly mounted into a left hand helical groove, and the working surface of each tooth of the metallic wire faces the rotational direction of the combing roller, the teeth of a terminal portion of the metallic wire adjacent to the flange at the end of the roller corresponding to the direction of progress of an imaginary left hand screw turned in the counter-clockwise direction when in imaginary engagement with the left hand helical groove, are bent toward the above mentioned flange, so that the axial size of the free space between said flange and said terminal portion can be reduced remarkably from that of the known combing roller. Utilizing the above described construction, the possible creation of the slubby yarn observed with the conventional combing roller can be effectively prevented. For the sake of simplifying the explanation presented hereinafter, the above-mentioned reduced free cylindrical; space is hereinafter referred to as a first free space, while the other free cylindrical space formed at a position between the other terminal portion of the metallic wire and the other flange is hereinafter referred to a second free space. Therefore, in the combing roller according to the present invention, the axial size of the first free cylindrical space is smaller than the second free space.